Composite wood-metal structural member



Nov. 22, 1966 D. RATLIFF, JR 3,286,429

COMPOSITE WOOD-METAL STRUCTURAL MEMBER Filed Sept. 9, 1963 INVENTOR.GEORGE D. RATL/FF, JR.

@ Attorney United States Patent ce 3286429 Patented Nov. 22, 1966 3 286429 attachment. After clinching, the spurs retain a degree of 9flexibility so that panel 13 is not rigidly attached to the COMPOSITESTRUCTURAL top chord but with slight limited freedom to come and GeorgeD. Ratlifi, Jr., Churchill Borough, Allegheny County, Pa., assignor toUnited States Steel Corporation, a corporation of Delaware Filed Sept.9, 1963, Ser. No. 307,403 1 Claim. (Cl. 52-727) This invention relatesto a composite beam and, in particular, to a composite beam havingconnections between its top chord member and web which are slightlyflexible so as to allow full stressing of the web material under load.

Composite beams of various types are known. All those with which I amfamiliar utilize rigid connections between the several members. Thus,where the members are of different materials, certain of them are notfully stressed under load. That is to say, the load is carried largelyby stress principally in one member and the use of material is not veryeflicient.

I have found that, by using connections between the members of acomposite beam which are somewhat flexible the web is stressed morefully than would be the case were the connections rigid. In a typicalexample, to be described in detail, a beam web of wood incorporating myinvention is stressed, under a given load, to almost double the value atwhich it would be stressed under the same load, using conventional rigidconnections.

A complete understanding of the invention may be obtained from thefollowing detailed description and explanation which refer to theaccompanying drawings illustrating the present preferred embodiment. Inthe drawings:

FIGURE 1 is an elevation of my beam with a part broken away; and

FIGURE 2 is an enlarged partial perspective similarly broken away.

Referring now in detail to the drawings, beam 10 there shown as anexample of my invention comprises a top chord 11, a bottom chord 12spaced therefrom and a web panel 13 extending between the chords andsecured thereto. One or more struts 14 may be incorporated, connectingthe chords 11 and 12. The beam is supported in any suitable manner, asby studs 15.

As shown in FIGURE 2, top chord 11 is a structural member such as a Zformed from sheet steel. Studs are similar. Bottom chord 12 is a woodstringer and panel 13 is of plywood. Strut 14 is also of wood. The panelfits flush against the flanges of chord 11 and studs 15 and the side ofchord 12. The flanges of the top chord and studs in contact with thepanel have spurs 16 struck out therefrom, adapted to be self-clinchingas the panel is pressed against the chord and studs for permanent gorelative thereto. This characteristic imparts the better stressdistribution between the chord and panel previously referred to.

Panel 13 may be secured to bottom chord 12 by nails or screws and,additionally or solely by adhesive, if desired.

In using my beam, stress in the web 13 increases as loads are applied.The stress is only partially transferred to the flange of chord 11,however, because of the flexibility of connecting spurs 16. In aspecific example where the web 13 is plywood and the chord 11 steel, aconventional rigid connection therebetween would result in a stress of1080 p.s.i. (strain 0.00067" per inch) in the web when the stress in thechord is 20,000 p.s.i. (strain 0.00067" per inch). With a proper degreeof flexibility in the connecting spurs 16, however, stress in the webcan be increased to the safe working value of the material which is 1875p.s.i. (strain 0.00117" per inch) while the stress in the chord remains20,000 p.s.i. (strain 0.00067" per inch).

It will be apparent that my invention permits the attainment of greaterefliciency in the use of material in composite beams than the rigidconnections ordinarily employed in such structures.

Although I have disclosed herein the preferred embodiment of myinvention, I intend to cover as well any change or modification thereinwhich may be made without departing from the spirit and scope of theinvention.

I claim:

A composite beam comprising a top chord member, a bottom chord memberspaced therefrom and a panel extending between and secured to saidmembers, said top chord member being a flanged metal member disposedwith its flange parallel to said panel and in abutting relationtherewith, said flange having flexible spurs extending therefrom andsaid panel being impaled on said spurs, whereby on initial loading ofthe beam, the resulting stress in the panel is only partiallytransferred to the top chord member.

References Cited by the Examiner UNITED STATES PATENTS 1,075,845 10/1913Mills 52731 1,328,201 1/1920 Rendano.

2,076,728 4/1937 Keller 52483 2,286,158 6/1942 Remmel et al 52-4832,339,841 1/ 1944 Deuchler et a1.

2,844,233 7/1958 Westman 287-189.36

FRANK L. ABBOTT, Primary Examiner.

R. A. STENZEL, Assistant Examiner.

